The present invention is generally related to lawn and garden equipment and more particularly related to a replaceable blade pruning device for cutting vegetation such as plant stems and branches.
Hand operated pruners are used in landscaping, horticulture and related fields to cut stems and small branches of plants. Pruners include a pair of hand grip portions that are operatively connected to a pair of opposing jaws. The jaws are opened and closed by manually opening and closing the hand grip portions. Often, one of the jaws defines a cutting edge and the opposing jaw defines a support surface that supports branches or stems being cut by the edge-defining jaw as the jaws move toward one another. It is important in many applications that the cutting edge of the pruner be sharp. A sharp cutting edge severs a branch or stem without crushing it, thereby minimizes damage to the plant or shrub. A sharp cutting blade also reduces the amount of hand pressure that must be applied to cut branches and stems, which is important to the operator, particularly when a large number of branches or stems have to be trimmed.
The cutting edge of some pruners is provided by replaceable blades. Standard replacement blades (of the type used in retractable blade utility knives, for example) are sharp, readily commercially available and relatively inexpensive. These standard blades are relatively thin, however, and tend to bend laterally or even break, particularly when cutting relatively large woody stems or branches. Thus, it would be desirable to provide a replaceable blade pruner that is better able to cut through relatively large or relatively woody stems without damaging the blade, or losing cutting efficiency due to bending of the blade.
Pruners also typically include locking assemblies which lock the jaws in their closed position. When the jaws are locked in their closed position, the cutting edge of one jaw is held very close to the support surface provided on the opposing jaw. Locking the jaws in their closed position therefore prevents accidental contact with the cutting edge of the pruner and thereby protects the cutting edge from damage.
Typically the grip portions of a pruner are biased by a spring or like mechanism into their open position. This biased grip and jaw movement is helpful to the worker when cutting a series of stems or branches because it allows the worker to open the jaws and the grip portions simply by releasing the grip portions. This spring biased opening action can be disadvantageous, however, when the pruners are not in use because the biasing force may cause the jaws to open accidentally, thereby exposing the pruner""s cutting edge. Locking assemblies frequently release, for instance, when the pruner is subjected to a relatively high magnitude impact force as, for example, when the locked pruners are dropped on the ground or tossed into a tool box. When the locking assembly releases, the cutting edge is immediately exposed because of the bias force applied to the jaws of the pruner. Thus, it would be desirable to provide an improved pruner locking assembly that is more likely to remain in its locked position even when the pruner is subjected to an impact force to prevent the cutting edge of the blade from accidentally being exposed.
The invention provides a pruning device for pruning and trimming vegetation that includes a pair of jaws movable relative to one another between open and closed positions. At least one of the jaws is a blade mounting jaw having a blade mounting portion. A relatively thin replaceable blade having a cutting edge is removably mounted on the blade mounting portion of the device such that the cutting edge cuts into vegetation positioned between the jaws as the jaws are moving toward and into their closed position. The device further includes a blade retainer that is movable between a blade retaining position and a blade releasing position with respect to the blade mounting portion. The blade retainer has a forward blade engaging portion. The blade retainer is constructed such that (a) in the blade retaining position thereof, the blade retainer secures the blade to the blade mounting portion with a forward edge portion of the blade adjacent the cutting edge being received between the forward blade engaging portion and the blade mounting portion, and (b) in the blade releasing position thereof, the blade retainer releases the blade to allow removal and replacement of the blade. The device also includes a rearward blade engaging structure that is constructed and arranged such that, when the blade is secured to the blade mounting portion by the blade retainer, a rearward edge portion of the blade adjacent the cutting edge is received between the rearward blade engaging structure and the blade mounting portion. The forward blade engaging portion and the rearward blade engaging structure thereby cooperate with the blade mounting portion to restrict lateral movement of the cutting edge of the blade when the blade is cutting vegetation. A pair of hand grip portions that are movable relative to one another are operatively connected to the jaws such that moving the hand grip portions relatively toward one another moves the jaws toward and into the closed jaw position thereof and moving the hand grip portions relatively away from one another moves the jaws toward and into the open jaw position thereof.
The invention also provides a pruning device for pruning and trimming vegetation comprising a pair of pruner members, each pruner member having a jaw portion and a handgrip portion. The pruner members are movably mounted to one another such that movement of the handgrip portions towards one another moves the jaws relative to one another to closed jaw positions and movement of the handgrip portions away from one another moves the jaws relative to one another to open jaw positions. At least one of the jaws provides a cutting edge operable in cooperation with the other jaw to cut into vegetation positioned between the jaws. The pruning device also includes a biasing structure that exerts a biasing force on the pruner members. The biasing force tends to move the grip portions away from one another and the jaws into the open jaw positions thereof. The pruning device further includes a lock structure operatively mounted on one of the pruner members and movable (a) in a releasing direction to a releasing position wherein the handgrip portions are released for movement from one another to move the jaws to the open jaw positions and (b) in a locking direction to a locking position wherein the lock structure engages a locking surface on the other pruner member to lock the handgrip portions together to maintain the jaws in their closed jaw positions.
The lock structure and the locking surface of the other pruner member are configured with respect to one another such that, when the handgrip portions are moved together to move the jaws into the closed jaw positions thereof and the lock structure is in the locking position thereof the biasing force of the biasing structure tends to move the handgrip portions away from one another thereby causing the locking surface to urge the lock structure in the locking direction to urge the lock structure to remain in the locking position thereof.
Other aspects, features, and advantages of the present invention will become apparent from the following detailed description, the accompanying drawings, and the appended claims.